The invention relates generally to agricultural machinery and, more particularly, to improvements to agricultural machinery for harvesting crops having an apparatus for contactless scanning of contours extending over the ground.
An apparatus generally of this kind is known from the article xe2x80x9cSwath Scanning with Ultrasoundxe2x80x9d (periodical: Landtechnik 5-93, pages 266-268). The apparatus described there consists of a plurality of ultrasound sensors which are arranged on a fastening strip at a distance of 40 cm from each other and are directed vertically onto the ground. This fastening strip may, for example, be mounted on agricultural equipment such as a forager or an agricultural machine towing a baling press. By means of the ultrasound sensors the height a swath, for example of straw or green fodder, above the ground can be determined at certain points, allowing the contour of the swath over the ground to be scanned along a horizontal line. The device described therein, however, has at least a few significant drawbacks. That scanning device is relatively expensive because several ultrasound sensors are necessary for scanning. Furthermore there is insufficient distance between the ultrasound sensors and, as a result, the ultrasound sensors have a disturbing effect on each other due to inadequate focusing of the sound lobes. This limits the horizontal resolution or density of measuring points of contour scanning.
Furthermore the distance of the ultrasound sensors from ground or the contour to be scanned must not become too great (not more than about 1.2 m.), because the resultant relatively high divergence of the sound lobes to the ultrasound sensors have a disturbing effect on each other. A sufficiently low height of mounting on the agricultural machinery is often difficult to achieve simply for structural reasons. Moreover such a bulky and low-set fastening strip with several ultrasound sensors is very easily damaged when used in the field. Increasing the height at which the fastening strip is set, however, is possible only if the distance between the ultrasound sensors on the fastening strip is also increased, which in turn means a lower horizontal resolution of swath contour scanning.
The attempt to reduce the minimum distance between the ultrasound sensors by implementing adjacent sensors that measure alternately, rather than simultaneously, requires an elaborate control circuit for the individual ultrasound sensors.
For forward-looking contour scanning such as would be necessary for example for automatic steering along the scanned swath contour, the fastening strip with the ultrasound sensors would have to be mounted in an elaborate and tedious manner on an additional holding linkage arranged at the front of the agricultural machinery and extended forwardly.
Another drawback of the known scanning apparatus lies in that the accuracy and reliability of scanning crop material by means of ultrasound greatly depends on the nature and properties of the crop material and on weather conditions.
Eggenhaus (U.S. Pat. No. 5,937,621) discloses an automatic system to control the cutting height and the reel height by an adjusting device which adjust the height of both by stored values. This system is needed if there is a change between standing and laying crop. Both, the cutting height and the reel height should be changed then. But if only the standing crop height changes, only the reel height must be changed without a change in the cutting height. This could be done by a manual adjustment from the operator. The absolute height of the stubble or the standing crop is not measured.
It is an object of the present invention to provide an apparatus on agricultural machinery for contactless scanning of contours extending over the ground, which eliminates the drawbacks of the devices described above. A further object of this invention is to provide a way to calculate the cross-sectional area.
A further object of this invention is to calculate an inclination offset.
A further object of this invention is to use the inclination offset when calculating contour information.
In accordance with the present invention, there is provided an agricultural machine having an apparatus for contactless scanning of contours extending over the ground comprising a laser distance measuring device, which has a laser beam transmitting and receiving device that determines the distance from a contour point by measuring the running time of the laser scanning beam emitted and reflected at the contour point. The laser scanning beams are pivotal within a certain angular range stepwise or steplessly in a scanning beam plane. In one embodiment the laser distance measuring device is mounted on the agricultural machine such that the scanning beam plane is inclined to the ground at an acute angle forwards in the direction of travel. With the aid of an analyzer, for each pivot angle from the measured distance, the arrangement and orientation of the laser distance measuring device on the agricultural machine (mounting height, angle of inclination to ground) is determined, as well as the position of the contour point corresponding to the pivot angle (vertical and horizontal position above the ground).
In accordance with another feature of the present invention there is provided a method of contour scanning during travel of an agricultural machine including the steps of providing a laser beam transmitting and receiving device; continually scanning the laser beam across the contour of the field in front of the machine; measuring the distance values from the laser beam; determine the contour of the field across the scanning width; and storing the contour information.
The use and arrangement of a laser distance measuring device embodying the invention has considerable advantages over the prior art scanning device described above.
Only one laser beam transmitting and receiving device is needed for the scanning device embodying the invention. Thus, this scanning device is considerably less expensive than the known ultrasound scanning device which requires several ultrasound sensors. The apparatus embodying the invention scans a contour in front of the agricultural machine at various points transverse to the direction of travel by pivoting the laser scanning beam. Thus the number of scanning points on a scanning line is substantially greater than with the ultrasound scanning device. Thus for example with a pivot angle range of xc2x145xc2x0 and pivoting of the laser scanning beam in 0.5xc2x0 steps, the result is 180 scanning points. Due to the low divergence of the laser scanning beam a relatively high resolution (density of scanning points) can be obtained, as the centers of adjacent scanning points lie close to each other without the scanning spots overlapping on the contour. Furthermore, unambiguous assignment of the point of reflection is possible.
Adjacent sensors do not adversely affect each other as with the prior-art scanning device, because the distances from the contour points are determined successively.
Scanning a significant distance ahead, such as is necessary for automatic steering along a scanned contour, can be achieved in a simple manner with the device embodying the invention. Thus, for example with a mounting height 380 cm. above the ground on an agricultural machine and an angle of inclination to the ground of 65xc2x0, a scanning distance in front of the agricultural machinery of approximately 8.15 m can be obtained. Due to the low divergence of the laser scanning beam, the scanning distance is not limited as in the case of ultrasound sensors. Contour scanning which may be achieved at relatively great distances cannot be achieved with the prior-art ultrasound scanning device. This would require a correspondingly long holding linkage in front of the agricultural machinery for receiving the fixing strip for the ultrasound sensors, which would cause the whole system to become completely impracticable.
Reflection of the laser scanning beam, unlike ultrasound, is relatively independent of any weather-related properties of the crop material to be scanned. Therefore, the possibilities of use of equipment utilizing the laser scanning device are increased with the present invention.
In a preferred embodiment the laser scanning beam is pivoted by means of a rotatable mirror or by means of a movable focusing device. Hence a relatively high number of scanning pivot paths per second and a high scanning frequency can be obtained, which is important particularly at higher traveling speeds. For example when using galvanometer motors for rotation of the rotary mirror, pivoting in a range of one millisecond is possible and, accordingly, a high scanning point density in the direction of travel of the agricultural machine can be obtained.
In an alternative embodiment for pivoting the laser scanning beam it is provided that the laser distance measuring device itself can be pivoted to pivot the laser scanning beam.
In one embodiment the laser distance measuring device is mounted within the driver""s cab, behind the windshield. Dust on the windshield can be filtered out of the signals and, thus, does not impair the reliability of scanning. Furthermore, the windshield itself also does not impair efficiency.
The scanning device embodying the invention can be used for the most varied applications owing to its high accuracy and reliability and its simple design and handling.
Thus, it is provided that, during travel of the agricultural machine continuously along the path covered, the contour across the scanning width is determined and stored. By this method the contour of swaths of crop material to be picked can be scanned and recorded very accurately. With the aid of the scanned contour, an analyzer determines the cross-section of the scanned swath of crop material over the ground base line in each case. This swath cross-section determination is used to adjust the traveling speed of the agricultural machine, wherein regulation can be adjusted for example to constant or maximum pick-up of crop material. With a decreasing swath cross-section the traveling speed is increased, so that the crop material picked up per unit of time is constant. If crop material-specific density data are available, these can also be linked to the measured swath cross-section. This information, in conjunction with a measured swath distance traversed and volume calculation, makes it possible to determine, on line, the crop material picked up during travel. Furthermore the swath-specific quantities determined in this way are in each case also used to adjust optimum working parameters of the harvesting machine.
In an advantageous embodiment of the invention, the right-of-way distance of the agricultural machinery determined within the pivot time of the scanning beam can be included in distance measurement as well.
In a particularly advantageous manner, the scanned swath contour, preferably the swath center, is used during swath pick-up for automatic steering of the agricultural machinery.
In conjunction with a real-time position finding system arranged on the agricultural machinery, such as a satellite navigation system or a global positional system (GPS), it is possible, over the whole area of use or over partial areas, to assign the scanned contours in each case to terrestrial coordinates (geographical length and width, if occasion arises height above NNxe2x80x94or Cartesian coordinates (x, y) referred to a point on the field). In this case, in addition to the swath-specific quantities, the distances between adjacent swaths are also determined and from them are generated surface area data or yield data. These are then stored for further use.
Using a sensor on the agricultural machinery which determines the inclined positions of the agricultural machinery for example when used on a slope, or when traveling in hollows or over ground undulations, in conjunction with a GPS position finding system arranged on the agricultural machinery, by scanning the ground contour, taking into account the inclined positions of the agricultural machinery and position, a high-precision, three-dimensional terrain model of the agriculturally useful area can be produced. The inclined positions of the harvesting machine can also be used for easy correction of the scanning distance.
Another use of the laser scanning device is to determine the distance of a corn ear surface from the harvesting machine. This signal is used to regulate the height of the cutter bar or reel, and relieves that responsibility from the operator. In this application the scanning distances measured can further be used to determine the actual load on the cutting mechanism. For this, the boundaries of the cutting mechanism are each assigned to a pivot angle of the laser scanning device. If a sudden change of contour takes place in this pivot range, there is a material edge at this point. Between this measured material edge and the boundary of the cutting mechanism furthest away, the load can then be determined. Should there be several sudden changes in the edge of the material due to lodging points in the standing crop, the sudden changes in material edge on the outside at any given time or one sudden change in material edge on the outside and one of the predefined boundaries of the cutting mechanism are used to determine the load on the cutting mechanism. This load value can then be recorded and/or used for more accurate surface area calculation.
Another use consists of scanning driving lanes which exist due to preceding working applications (e.g. sowing and application of crop protection agents) in a standing crop, wherein automatic steering of the harvesting machine is carried out by known means with the aid of these scanned driving lanes.
Another advantageous use of the laser scanning device is the scanning of cultivation tracks. Such scanning during cultivation provides a means by which a agricultural machine can be steered automatically along a scanned track. This device is particularly suitable for scanning tracks or furrows such as those arising when plowing. Here the wide range of cover of the device proves to be particularly advantageous. In case of a reversal of the direction of cultivation, the laser scanning device does not have to be pivoted mechanically. Only the regulating signal has to be provided with an altered offset and fed to the automatic steering device. For this purpose for example sensors present on a plow can determine the position of the plow frame and convey it to the analyzer or steering regulator device. The offset can further be influenced manually or by an inclined position measuring means of the agricultural machinery.
In another embodiment the laser scanning device allows a subsequent cultivation track only in the preselected identical direction of cultivation (e.g. general-purpose plow, cutter bars), can be mounted directly over the lane or cultivation edge on the cultivation implement or agricultural machine or harvesting machine. Conversion of the measured track position or addition of an offset can then be eliminated.
On the basis of the laser scanning device, precautionary methods can be implemented for operation of the agricultural machinery. If a preset threshold value for the increase in height and/or the absolute height of a scanned contour in the direction of travel is exceeded, a caution signal is generated for the operator. Hence the driver is given notice of undulations of the ground or obstacles which could lead to implement damage.
Obstacles (e.g. poles for overhead power lines, trees, rocks, etc.) which, owing to their vertical extent, do not lie within a permitted range of contour expectation values can be detected on the field by means of the laser scanning device.